Collimating optical sight



Dec. 27, 1949 A. D. ROBBINS 2,492,888

COLLIMATING OPTICAL SIGHT Filed Nov. 26, 1946 2 Sheets-Sheet 2 IN V ENTOR.

Patented Dec. 27, 1949 COLLIMATING OPTICAL SIGHT Azor D. Robbins, GlenCove, N. Y., assignor to Specialties, Inc.

Application November 26, 1946, Serial No. 112,300

The present invention relates to gun sights of a type having a combiningglass through which the target is seen and in whicha reticule image isreflected to indicate the line of sight to the target,

and has for an object to providean improved control for the movement ofthe reticule image in the combining glass.

In combat airplanes it is possible to compute the angle of lead for gunscarried by. n attacking plane and trained on a target plane travelingacross the path of the attacking plane. The angle of lead in some casesis relatively high because of the relative movement between th attackingplane and the target plane. The present invention aims to provide asight unit having a wide angle of movement of the line of sight asrequired for such combat conditions.

The invention has for an object also to provide a large field ofmovement and accuracy of movement of the reticule. Still another objectis to provide a universal sight unit adaptable for use for various typesof projectiles including rockets and the like. g

Another object is to provide a movable image in which the image movementin both coordinates will be uniform throughout its travel in relation tothe angular movement of the driving shafts.

Another object is to provide a relatively fixed reference reticuleadjustable for bore sighting but relatively fixed as compared with thelead-indicating movable reticule image.

Another object is to provide an improved sight unit having both a fixedreticule image and a movable reticule image in the combining glass.

Another object is to provide a sight unit having a fixed and a movablereticule image arranged for separate illumination and in whichparticularly bright illumination of either or bothimages can beobtained. I

The sight unit to be described for the purposes of illustration includesacombining glass with a collimating lens beneath the glass and closebelow 4 Claims. (01. 88-1) the lens a universally tiltable mirrorreflecting manner as to afiord a rectilinear pattern of movement of thereticule image and therefore of the line of sight. I

The nature and object of the invention will be better understood from adescription of a particular illustrative embodiment of the invention forthe purposes of which description reference should be had to theaccompanyin drawings forming a part hereof and in which Figure 1 is alongitudinal sectional view of a sight unit embodying the invention, r

Fig. 2 is a sectional plan view taken on the line 2-2 of Figure 1, v

Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. 4,

Fig. 4 is a vertical sectional view taken on the line 4--4 of Fig. 2,and

Fig. 5 is a detail View of the principal mirror.

In the sight unit shown the pilot views the-tar-- get through thecombining "glass 5 and at the same time sees in the combining glass animage of the reticule to give him the line of sight. The reticule isshown at fi illuminated by a lamp 1 with a mirror 8 tiltable about the:axis 9 to reflect light from the reticule through the collimating lensIn which forms an image of the reticule at infinity. The pilot sees thisimage reflected in the combining glass and. since the image is formed atinfinitive, hesees it as coincident with the target when he is flyingaccurately with the sight on the target. The mirror 8 is rocked aboutthe transverse axis 9 to move the reticule image in a vertical planethereby raising or lowering the line of sight. -The mirror is tiltedlaterally about a substantially longitudinal axis I l tomove the imageof the reticule laterally in the combiningglass and thereby swing theline of sight.

laterally. Y l

If the mirror 8 is moved about the axis 9 in equal arcs and about theaxis II in equal arcs, the pattern of movement of the line of sight willbe trapezoidal for the reason that when the mirror is tilted at a moreacute angle to the axis of the lens lateral tilting about the axis I lmoves the image through a'wider arc.' This is corrected in the mechanismshown to. provide a rectangular pattern of movement by causing thelateral tilting movement to be correspondingly smaller when the mirroris at a more acute angle to the axis of the collimating lens.

The mirror mounting comprises a yoke l4 pivoted for movement about thetransverse axis 9 with a frame l5 in which the mirror is carried securedto a shaft l6 rotatable in a bearing in the yoke [4 on the axis ii. Thedepending arm of the mirror frame terminates in the ball I I which fitsbetween the parallel cheeks i8 of lever I9 pivoted at 20. Asthe lever [Bis moved laterallyQthe extent of lateral swing of the mirror 8 willdepend upon the distance of the ball'end I! from the pivot 20 of thelever 19.

been obtained by making the angle between shafti l8 and the plane of themirror 8 between 35? and 40 but this angle can be varied considerablyifthe proportions of other parts are; correspondingly modified.

The movement 01' the mirror. in the fore and aft direction and laterallyis controlled by servo mechanisms, of which motors 22 and 3m provide.

power, responsive to computers which give the ortheline or sightim twoco,- therei'ore, determines the; position of the mirroriprxvariousrconditionsr of gravity arse. a h nr newing mo ntsar and thelike. Tlrefsenvamotor for rotating the abo -th ra e s axis 91 i in c at22 in Figs. 2 and 4. This motor drives a. gear t. H: seeupodztm the yoke7 It throu h earing including pinion 22', gear 22! a; worm 2-4;worm-wheelsfl hattjiand pinion-11'. Gear'22 drives lead screw 28 whichmoves; a. contact. along 26;,- iorming aipartlotthe servo omltmil.

5cm [motor 1a .ms. l and. 2, actuates lever. it through suitable:gearing; including: pin-1on1 30.; sent 8M1, wornr It, worm wheel 32-;shaft: 3%; pinion; #111335; andithe anti-friction roller '35carrdedibythe gearsegment; and: operate ingrhetmeen: the-cheeks: i8.of:-the lever l8. Gear at iscfixedaonanddritesz lead screw 31 whichmoves? at contact along potentiometer 31* forminga partotitheservoecontrol- It-is be.- noted that the movement ota the bailendI 1 of lever It between the. cheeks. i8 oi the levev w introduces acertaindeviation from inaccurate proportional movement; However,

movement: on the lever" t9: by the gear: segmenitwis sncltasto provide asuitable-compensatiomi'br such deviation by the-following means.-

Referringto- Fig: 3'; it" can be seenthat to produce'unitorin angularmovement of lever l5 as viewed in this position, it will be necessary todisplacecheeks H laterally in proportion to the sineot'said lever angle.Roller -36 which operated as, the driving" means for saidcheeks willdisplace them" lateraliydn proportion to-the sine of anguifar movement:of segment 35-. Thus, by. choosing. suitable lengths of lever arms itispossihle to match the sine movements and establish proportionallyuniform angular movements. in lever. lilalidf gear. segment 35throughout their r It is desirable for the pilot; to. knowin whichdirectionlirom. normal central, bore sight position the. retlculeimage.has been. moved or atwhat. ismoving. For. this. purpose asecondflxedreierencereticule 38 which may be designatedthe "boresightreticule is provided. This; reticule is optically on the. centerline of the 1-0 and atthersames distance from thoz-lens alongianbptical;as the reticule 6; theiocal length of. the lens in stdetzill t-t et tcmelmae y alsa i used a fi y c mmun sm: q r P images.

sitioning this second reticule on the axis of the lens, it may bepositioned at one side as indicated in Fig. 3, and illuminated by a lamp39. A mirror 40 is suitably positioned on the lens axis beneath themirror 8 to reflect the image. The mirror 40 is carried by an adjustablebracket 4| in order that it may be adjusted for the purposes of boresighting.

The" twmlamp se I and 39s illuminating the respective reticuiesshouldbeso chosen as to provide the desired relative brightness of the twoOrdinarily it is preferable to have the movable: of the reticule 6substantially brighter than the fixed reticule because this is*thereticule image which the pilot maintains on the target. The desiredrelative brightness man-'aismbepbtainediby making the reflection andtransmission of light 01' the mirror of suitable proportions.

The mirror 8 is semi-reflecting and semitransparent inorder that' lightfrom the reticule 6 may be-reflected therebyandli'ght from the reticule38*as reflected' bymirror 40zmay-passthrough to the collimating lens:The mirror shown ls a thin transparent plastic element to which, isapplied a: reflectivecoating 8 adapted; to reflect and transmitsubstantially equal amounts'of'light.

The foregoing: particular description is illustrative merelyand'is notintended as defining thelimits oi" the invention; Various modificationsandadaptations' canbe made without departing fromgthe' spirit of theinvention. as deflned'in;the-clai1ns-.-,..

I claim;

1. In a sight unit, in combination, a casing, a combining glass; areticule andia collimating lens fixed in the casing, a tilt'able mirrorpositioned to reflect lighti'rom' the reticule through the collimatinglens-to the'combining glass to provide a line of sight; a; supportingyoke pivoted in the casing onartmnsverse'axis-beneath the collimatinglens for foreand aft tilting movement to. raise and lower the line of.sight, aframecarryingsaid mirror'pivotedon saidsupporting'yoke forlateral tilting movementtomoye the. line of sight lat erally andhavingadepen'dlng arm; a slotted'lever pivoted in" the casingfor lateralmovement, engageable with saiddepending. arm to move the depending: arm-latera1iy,-said' depending arm being movable in the slot of the slottedlever toward andirom the-pivot of the lever whereby the extent oilateral movement ofthe depending arm willvary with the position of thearm in the slot, and means-.i'or: moving said slotted: lever-laterally.

2. In a sight' unit of the character described, in', combination; a"casing, a: combining glass, a reticule and a collimating lens beneaththe combining glass fixed" in the: casing, a tiltable semitransparentmirror positioned beneaththe collimating lens to reflect light from thereticule through the collimating' lensto the" combining glass to-provide or line of sight; a; supporting yoke pivoted'torcck-on a transverseaxis" beneath the collimating-lens; a frame inwhich said mirror ismounted pivoted on said yoke iorlateral tiltlug-movement, the. axis-:01the pivot of'said frame lying at an angle of between 35fand 45 to theplane of the mirror', a second mirror positioned beneath the semirtransparent mirror, and a second'reticnlle. positlonedlm be,reflected by said second mirror along the axis of the eliminating lens;to thacombinino glass.- to provide a. second lineot sight,

3-. Adieu-unit to claim: L. in which there is mounted within the casingan electric motor actuated by remote control to drive gearing to rotatesaid supporting yoke about said transverse axis, and a second electricmotor also actuated by remote control to drive gearing to move saidslotted lever laterally.

4. In a collimating optical sight, in combina tion, a casing; acombining glass external of said casing; a collimating lens fixed insaid casing; a first reticule illuminated by a first source of light; asemi-transparent, semi-reflecting mirror positioned to reflect the imageof said first reticule through said collimating lens onto said combiningglass to establish a first line of sight; a support for said mirrorpivoted in the casing for movement on a transverse axis and for movementlaterally at a right angle to said transverse axis to cause said firstreticule to move on said combining glass both horizontally andvertically; a second reticule illuminated by a second source of light,positioned in fixed position beyond said mirror and visible coaxial withsaid collimating lens through said mirror on said combining glass toestablish a fixed second line of sight; a first servomechanism withinsaid casing acting upon receipt of a signal to tilt said mirror supporton its transverse axis; and a second servomechanism within said casingacting upon receipt of a signal to tilt said mirror support onlaterally.

AZOR. D. ROBBINS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,783,769 Bates Dec. 2, 19302,162,698 Chafiee et al June 20, 1939 2,322,395 Sheppard June 22, 19432,368,959 Winslow Feb. 6, 1945 2,379,894 Esval et a1 July 10, 19452,409,648 Auken et al Oct. 22, 1946 2,428,870 Essex Oct. 14, 19472,434,109 Harasta Jan. 6, 1948 FOREIGN PATENTS Number Country Date776,640 France Nov. 8, 1934 837,661 France Nov. 18, 1938

